A326385 Oblong numbers m such that beta(m) = tau(m)/2 where beta(m) is the number of Brazilian representations of m and tau(m) is the number of divisors of m.

3906, 37830, 97656, 132860, 1206702, 2441406, 6034392, 10761680, 21441530, 96855122, 148705830, 203932680, 322866992, 747612306, 871696100, 1187526060, 1525878906, 1743939360, 2075941406, 3460321800, 5541090282, 8574111812, 9455714840, 12880093590, 18854722656

Offset

1,1

Comments

The number of Brazilian representations of an oblong number m with repdigits of length = 2 is beta'(n) = tau(n)/2 - 2.

This sequence is the second subsequence of A326380: oblong numbers that have exactly two Brazilian representations with three digits or more.

Links

Chai Wah Wu, Table of n, a(n) for n = 1..129

Index entries for sequences related to Brazilian numbers

Example

3906 = 62 * 63 is oblong, tau(3906) = 24, beta(3906) = 12 with beta'(3906) = 10 and beta"(3906) = 2: 3906 = 111111_5 = 666_25 = (42,42)_92 = (31,31)_125 = (21,21)_185 = (18,18)_216 = (14,14)_278 = 99_433 = 77_557 = 66_650 = 33_130 = 22_1952.

Crossrefs

Cf. A000005 (tau), A220136 (beta).

Subsequence of A002378 (oblong numbers) and of A167783.

Cf. A326378 (oblongs with tau(m)/2 - 2), A326384 (oblongs with tau(m)/2 - 1), A309062 (oblongs with tau(m)/2 + k, k >= 1).

Sequence in context: A252138 A115468 A066386 * A068240 A022212 A131409

Adjacent sequences: A326382 A326383 A326384 * A326386 A326387 A326388

Keyword

nonn,base

Author

Bernard Schott, Jul 10 2019

Extensions

a(6)-a(25) from Giovanni Resta, Jul 11 2019

Status

approved